The goal of this proposal is to investigate methods and techniques for reliable ultrasound scanning to obtain quantitative images of several acoustic parameters within two-dimensional cross sections of the breasts of patients ina period of a few minutes The instrument will synergistically combine these quantitative multimodal images to obtain diagnosis of breast disease. Ultrasound computer-assisted transmission tomography will be utilized to obtain qualtitative cross-sectional images of acoustic speed, acoustic attenuation, acoustic absorption and scatter and reflection where appropriate. Both analytic and iterative methods of correcting aberrations in the images caused by inhomogeneous refractive index will be investigated. A clinical scanner will be built in which patients scheduled for surgical biopsy will be scanned and by the resulting images compared to the histological results of biopsy and/or surgical mastectomy. Comparisons between surgical specimens and acoustic images will be made usingmethods of automated computer-assisted pattern classification and recognition combined with histologic methods of tissue preparation specifically designed to aid in comparing with ultrasound images of the coronal plane of the intact breast with similar planes through the excised breast. This parallel investigation of the clinical instrument and imaging method, the tissue analysis techniques, and the pattern recognition programs should result in complete evaluation of a prototype clinical instrument capable for use in the high volume clinical environment. ?999